Unless it's a rifled barrel and you're launching sabot slugs 150+ yards, no. Actually, it should lock up just about the same place when you reinstall. Now, vibration and barrel play have more of a role in accuracy than taking the barrel off and reinstalling it. Those guys who want a super-accurate slug gun usually fix the barrel to the receiver and don't remove the barrel anymore. It makes for more complicated cleaning, but it works. Your best bet, though, is to enjoy some range time and try it out. Slugs will show you the POI shift the best, so get a couple boxes, go to the range, and experiment. I'd bet that at the ranges you're probably going to shoot, you're going to be fine.